Ounjaijean S, Thephinlap C, Khansuwan U, Phisalapong C, Fucharoen S, Porter J B, Srichairatanakool S
Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
Med Chem. 2008 Jul;4(4):365-70. doi: 10.2174/157340608784872316.
Plasma non-transferrin bound iron (NTBI) is potentially toxic and contributes to the generation of reactive oxygen species (ROS), consequently leading to tissue damage and organ dysfunction. Iron chelators and antioxidants are used for treatment of thalassemia patients. Green tea (GT) contains catechins derivatives that have many biological activities. The purpose of this study was to investigate the iron-chelating and free-radical scavenging capacities of green tea extract in vivo. Rats were injected ip with ferric citrate together with orally administered GT extract (GTE) for 4 months. Blood was collected monthly for measurement of iron overload and oxidative stress indicators. Plasma iron (PI) and total iron-binding capacity (TIBC) were quantified using bathophenanthroline method. Plasma NTBI was assayed with NTA chelation/HPLC. Plasma malonyldialdehyde (MDA) was determined by using the TBARS method. Erythrocyte oxidative stress was assessed using flow cytometry. Levels of PI, TIBC, NTBI and MDA, and erythrocyte ROS increased in the iron-loaded rats. Intervention with GT extract markedly decreased the PI and TIBC concentrations. It also lowered the transferrin saturation and effectively inhibited formation of NTBI. It also decreased the levels of erythrocyte ROS in week 4, 12 and 16. Therefore, green tea extract can decrease iron in plasma as well as eliminate lipid peroxidation in plasma, and destroy formation of erythrocyte ROS in the rats challenged with iron. The bifunctional effects could be beneficial in alleviating the iron and oxidative stress toxicity. In prospective, these GTE activities should be further examined in thalassemic animals or humans.
血浆非转铁蛋白结合铁（NTBI）具有潜在毒性，会促使活性氧（ROS）生成，进而导致组织损伤和器官功能障碍。铁螯合剂和抗氧化剂用于治疗地中海贫血患者。绿茶（GT）含有具有多种生物活性的儿茶素衍生物。本研究旨在探讨绿茶提取物在体内的铁螯合和自由基清除能力。给大鼠腹腔注射柠檬酸铁并同时口服GT提取物（GTE），持续4个月。每月采集血液以测量铁过载和氧化应激指标。采用邻二氮菲法对血浆铁（PI）和总铁结合力（TIBC）进行定量。用NTA螯合/HPLC法测定血浆NTBI。采用硫代巴比妥酸反应物（TBARS）法测定血浆丙二醛（MDA）。使用流式细胞术评估红细胞氧化应激。铁负荷大鼠的PI、TIBC、NTBI和MDA水平以及红细胞ROS升高。用GT提取物干预可显著降低PI和TIBC浓度。它还降低了转铁蛋白饱和度并有效抑制了NTBI的形成。在第4周、12周和16周时，它还降低了红细胞ROS水平。因此，绿茶提取物可降低血浆中铁含量，消除血浆中的脂质过氧化，并在铁攻击的大鼠中破坏红细胞ROS的形成。这些双重作用可能有助于减轻铁和氧化应激毒性。展望未来，应在患地中海贫血的动物或人类中进一步研究这些GTE活性。
